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Finding the Fourth Proportional to 252.40, 378.55 and 81.40

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Solution

The fourth proportional to 252.40, 378.55 and 81.40 is: 122.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    252.40 : 378.55 = 81.40 : x
  2. Step 2: Convert to fraction form
    252.40/378.55 = 81.40/x
  3. Step 3: Cross multiply
    252.40x = 378.55 × 81.40
  4. Step 4: Simplify right side
    252.40x = 30,812.08
  5. Step 5: Solve for x
    x = 30,812.08/252.40
  6. Step 6: Final answer
    x = 122.08

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.